This is a continuation of PCT/DE 00/02760, filed Aug. 16,2000.
1. Field of the Invention
The present invention relates to a vertebral column segment for implanting into a human vertebral column.
2. Description of Related Art
Many people suffer from a diseased or damaged intervertebral disc (also called spinal disc). Genuine healing of this intervertebral disc is not possible for the intervertebral discs mainly consist of cartilaginous tissue and cannot regenerate.
The German Patent No. DE 196 32 404 A1 discloses a transplantable cartilage tissue consisting of a new extracellular matrix (ECM) that sets free matrix molecules, immunosuppressive or cell differentiating factors in response to gene manipulation, the cartilage tissue being surrounded by a semipermeable membrane. This cartilage tissue is suited for joints but not for replacing an intervertebral disc, though.
In view thereof, it is the object of the present invention to provide a vertebral column segment for implanting into a human vertebral column that is available in sufficient quantity.
The technical solution to this object according to the invention is to form a vertebral column segment for implanting into a human vertebral column that comprises a vertebral body insert and/or an intervertebral disc with the associated upper and/or lower fragment of a vertebral body and/or a vertebral arch, more specifically provided with the diverse processes, the intervertebral disc being made from a gene manipulated animal intervertebral disc or the vertebral body insert, the fragments of the vertebral body, the vertebral arch and/or the processes being made from gene manipulated animal bones.
The present invention is based on the findings that a transgenic animal intervertebral disc and/or a transgenic animal bone, more specifically from a pig or a sheep, is in principle also suited for implantation into a human spine.
A vertebral column segment formed according to this technical teaching has the advantage that intervertebral discs and associated vertebral bodies can thus be provided as required and in sufficient quantity.
It thereby proved advantageous to genetically manipulate the corresponding transgenic animal intervertebral discs or vertebral body inserts or fragments of vertebral bodies or vertebral arches or their processes in such a manner that these elements have, as close as possible, the same blood group, more specifically the same subgroup, the same tissue structure and/or the same bone structure as the human vertebral column into which they are to be implanted.
This positively influences the successful in-growth into the human spine and the implant is unlikely to be rejected by the human body as a result thereof.
The intervertebral disc of both the human and the animal vertebral column is tightly connected to the adjacent upper or lower vertebral body and is only kept in the correct position on account of this tight connection. A once dissociated intervertebral disc proved to have difficulties in growing on again on the vertebral body; it is therefore advantageous to implant the intervertebral disc together with the vertebral body situated underneath and/or above it or at least with an appropriate fragment of vertebral body. In order to quickly grow the implant to the size wanted and/or in order for the implant to quickly grow into the human spine, the growth of the animal bone is accelerated by means of a nutrient solution and/or a growing factor. This nutrient solution may for example be hydroxylapatite (also called coral limestone) which stimulates bone formation.
To remove the diseased and damaged spinal disc, the adjacent vertebral bodies are advantageously severed with a clean cut. This also facilitates the formation of the implant. After the implant is inserted into the appropriate location in the human spine, the implant is fixated to the two parts of the divided vertebral body utilizing a clip. Such a clip is advantageously given the shape of a U and its edges are so sharp that the clip may be pressed by its free ends into the two parts of the respective one of the vertebral body.
In an alternative embodiment, the spinal disc is replaced by a vertebral body insert that is exclusively made from gene manipulated animal bone?. Although the corresponding portion of the vertebral column becomes permanently stiff as a result thereof, implantation of this vertebral body insert is less problematic.
Other examples of gene manipulation of bone, in addition to DE 19632404, are disclosed in U.S. Pat. Nos. 5,849,993, 6,235,969, and 6,444,205, the disclosures of which are incorporated herein by reference.
In an alternative embodiment, it proved advantageous to fasten the fragments of the vertebral body and/or the vertebral arch by means of at least one screw, more specifically of a so-called BioScrew or of a BioPin. This also permits to reliably secure the implant.
In a preferred development, the screw is so long and so thin that the screw extends through the vertebral arch into the vertebral body; this provides for a reliable fixation of the implant as well.
In still another preferred embodiment, the screw ends in a counterpart that is provided with a corresponding internal screw thread, the counterpart being introduced into the vertebral body from the opposite side and being kept positively locked within the vertebral body. As a result thereof, the implant is interlocked with and very reliably connected to the human spine.
Further advantages of the vertebral column segment in accordance with the invention will become apparent in the accompanying drawing and in the following description of embodiments. Also and in accordance with the invention, the features mentioned herein above and those still to be discussed can be used either individually or in any combination. The embodiments mentioned are to be considered only as illustrative and not restrictive.